In one example, image guided surgery (IGS) uses preoperative patient images to guide a subsequent medical procedure. The preoperative patient images are displayed on computerized IGS workstation. A surgical instrument is remotely tracked by an optical or other positioning system that is coupled to the IGS workstation. This permits an image of the instrument and/or its trajectory path to be displayed on the preoperative patient images, which, in turn, helps the surgeon plan the entry point and trajectory to a desired target location within the patient. In one example, the light emitting diodes (LEDs) or passive reflectors are attached to the surgical instrument. The optical positioning system includes a camera that can detect light from such locators to determine the position and orientation of the surgical instrument.
In another example, IGS uses intraoperative patient images to guide an ongoing medical procedure. In one such example, a trajectory guide is mounted to a patient's skull, which, in turn, is introduced into a magnetic resonance (MR) imaging apparatus. MR images obtained during the medical procedure are used to guide the procedure, which may involve adjusting the skull-mounted trajectory guide to obtain the desired trajectory toward a target in the patient's skull, and then inserting a medical instrument through a guide lumen of the trajectory guide, along the trajectory path, to the target location in the patient's skull. The present inventors have recognized, among other things, that when MR intraoperative imaging is being used to guide an ongoing medical procedure, the medical instruments being used in the procedure must be MR-compatible.